1. Technical Field
The present invention relates to a spectroscopic measurement apparatus, a driving circuit, and a spectroscopic measurement method, etc.
2. Related Art
A spectroscopic measurement apparatus that includes a wavelength variable interference filter is known. For example, a spectroscopic measurement apparatus disclosed in JP-A-2013-092474 is provided with a wavelength variable interference filter that includes a pair of reflection films facing each other, wherein the distance between the pair of reflection films is changed in accordance with measurement wavelength. In the spectroscopic measurement apparatus disclosed in JP-A-2013-092474, an electrostatic actuator that changes a distance between the pair of reflection films is provided, and an analog voltage that changes in a continuous manner is applied to the electrostatic actuator. The voltage applied to the electrostatic actuator is monitored. When the monitored voltage becomes equal to a predetermined measurement voltage, transmitted light that has passed through the wavelength variable interference filter is detected by a detection unit.
In the apparatus disclosed in JP-A-2013-092474, the velocity at which the distance between the pair of reflection films changes (distance change velocity) varies in a sinusoidal wave pattern when the analog voltage is applied to the electrostatic actuator for cyclic driving. In this case, the gap change velocity is not constant when the light outputted from the wavelength variable interference filter is detected by the detection unit and, therefore, non-uniformity in measurement wavelength interval appears when the signal from the detection unit is acquired at a constant time interval. That is, the measurement wavelength interval is dense at a position of a low distance change velocity and is sparse at a position of a high distance change velocity. In JP-A-2013-092474, in which the voltage applied to the electrostatic actuator is monitored and the signal from the detection unit is acquired when the monitored voltage becomes equal to a predetermined measurement voltage, it is difficult to obtain the results of measurement for each measurement wavelength with a predetermined measurement wavelength interval just by performing scan once at a position of a high distance change velocity. In such a case, it is necessary to perform scan plural times and, therefore, it takes long to complete the measurement.